Bessel van der Kolk claimed the following in The Body Keeps the Score:
There have in fact been hundreds of scientific publications spanning well over a century documenting how the memory of trauma can be repressed, only to resurface years or decades later. Memory loss has been reported in people who have experienced natural disasters, accidents, war trauma, kidnapping, torture, concentration camps, and physical and sexual abuse. Total memory loss is most common in childhood sexual abuse, with incidence ranging from 19 percent to 38 percent. This issue is not particularly controversial: As early as 1980 the DSM-III recognized the existence of memory loss for traumatic events in the diagnostic criteria for dissociative amnesia: “an inability to recall important personal information, usually of a traumatic or stressful nature, that is too extensive to be explained by normal forgetfulness.” Memory loss has been part of the criteria for PTSD since that diagnosis was first introduced.
One of the most interesting studies of repressed memory was conducted by Dr. Linda Meyer Williams, which began when she was a graduate student in sociology at the University of Pennsylvania in the early 1970s. Williams interviewed 206 girls between the ages of ten and twelve who had been admitted to a hospital emergency room following sexual abuse. Their laboratory tests, as well as the interviews with the children and their parents, were kept in the hospital’s medical records. Seventeen years later Williams was able to track down 136 of the children, now adults, with whom she conducted extensive follow-up interviews. More than a third of the women (38 percent) did not recall the abuse that was documented in their medical records, while only fifteen women (12 percent) said that they had never been abused as children. More than two-thirds (68 percent) reported other incidents of childhood sexual abuse. Women who were younger at the time of the incident and those who were molested by someone they knew were more likely to have forgotten their abuse.
This study also examined the reliability of recovered memories. One in ten women (16 percent of those who recalled the abuse) reported that they had forgotten it at some time in the past but later remembered that it had happened. In comparison with the women who had always remembered their molestation, those with a prior period of forgetting were younger at the time of their abuse and were less likely to have received support from their mothers. Williams also determined that the recovered memories were approximately as accurate as those that had never been lost: All the women’s memories were accurate for the central facts of the incident, but none of their stories precisely matched every detail documented in their charts. [...]
Given the wealth of evidence that trauma can be forgotten and resurface years later, why did nearly one hundred reputable memory scientists from several different countries throw the weight of their reputations behind the appeal to overturn Father Shanley’s conviction, claiming that “repressed memories” were based on “junk science”? Because memory loss and delayed recall of traumatic experiences had never been documented in the laboratory, some cognitive scientists adamantly denied that these phenomena existed or that retrieved traumatic memories could be accurate. However, what doctors encounter in emergency rooms, on psychiatric wards, and on the battlefield is necessarily quite different from what scientists observe in their safe and well-organized laboratories.
Consider what is known as the “lost in the mall” experiment, for example. Academic researchers have shown that it is relatively easy to implant memories of events that never took place, such as having been lost in a shopping mall as a child. About 25 percent of subjects in these studies later “recall” that they were frightened and even fill in missing details. But such recollections involve none of the visceral terror that a lost child would actually experience.
Another line of research documented the unreliability of eyewitness testimony. Subjects might be shown a video of a car driving down a street and asked afterward if they saw a stop sign or a traffic light; children might be asked to recall what a male visitor to their classroom had been wearing. Other eyewitness experiments demonstrated that the questions witnesses were asked could alter what they claimed to remember. These studies were valuable in bringing many police and courtroom practices into question, but they have little relevance to traumatic memory.
The fundamental problem is this: Events that take place in the laboratory cannot be considered equivalent to the conditions under which traumatic memories are created. The terror and helplessness associated with PTSD simply can’t be induced de novo in such a setting. We can study the effects of existing traumas in the lab, as in our script-driven imaging studies of flashbacks, but the original imprint of trauma cannot be laid down there. Dr. Roger Pitman conducted a study at Harvard in which he showed college students a film called Faces of Death, which contained newsreel footage of violent deaths and executions. This movie, now widely banned, is as extreme as any institutional review board would allow, but it did not cause Pitman’s normal volunteers to develop symptoms of PTSD. If you want to study traumatic memory, you have to study the memories of people who have actually been traumatized.
At some point I tried to read some papers on the topic to see what the state of the debate is; here’s what I wrote about it in another post:
This post discusses suppressing traumatic memories, drawing on the theories of clinical practitioners, who have disagreements with clinical researchers about whether memory suppression is a thing (Patihis, Ho, Tingen, Lilienfeld, & Loftus, 2014).
Much of the criticism about repressed memories is aimed at a specific concept from Freudian theory, and/or on the question of how reliable therapeutically recovered memories are. Several of the critics (e.g. (Rofé, 2008)) acknowledge that people may suppress or intentionally forget painful memories, but argue that this is distinct from the Freudian concept of repression. However, memory suppression in the sense discussed in this post is not related to the Freudian concept, and also includes intentional attempts to forget or avoid thinking about something, as the examples will hopefully demonstrate.
In fact, the memories being hard to forget is exactly the problem, which is something that many critics of the standard Freudian paradigm are keen to point out—traumatic memories are often particularly powerful and long-lasting.
I do make the assumption that conscious attempts to forget something may eventually become sufficiently automated so as to become impossible for the person themselves to notice; but this seems like a straightforward inference from the observation that skills and habits in general can become automated enough so as to happen without the person realizing what they are doing. A recent experiment (unreplicated, but I have a reasonably high prior for cognitive psychology experiments replicating) also showed that once people are trained to intentionally forget words that are associated with a particular cue, the cue will reduce recall of words even when it is paired with them in a form that is too short to consciously register (Salvador et al. 2018).
I make no strong claims about the reliability of memories recovered in therapy. It has been clearly demonstrated that it is possible for therapists to accidentally or intentionally implant false memories, but there have also been cases of people recovering memories which have then been confirmed from other sources. Probably some recovered memories are genuine (though possibly distorted) and some are not.
Bessel van der Kolk claimed the following in The Body Keeps the Score:
At some point I tried to read some papers on the topic to see what the state of the debate is; here’s what I wrote about it in another post: